I/7559: Update ImageResizeUI plugin

[panr]

Suggested merge commit message (convention)

Other (image): Improved ImageResizeUI plugin UI. Added the dedicated icons for each option (small, medium, large and original) and the dropdown (dropdown icon). Closes #7559.

Other (image): Improved screen reader experience for ImageResizeUI standalone buttons in the image.toolbar.

Other (core): Added icons that represent the size of the element (object-size-*).

[oleq]

Couldn't we have something like this to save space in the toolbar?

.ck.ck-dropdown .ck-button.ck-resize-image-button .ck-button__label {
    width: 4em;
}

[panr]

Phew... I fixed them all 😅

[oleq]

I improved some docs and refactored the code a little bit. Still:

• Localization entries are missing.
• Missing changelog entry for ckeditor5-core.
• Docs are bleeding (CKEditorError: imageresizeui-missing-icon) http://fake.ckeditor.com/ck/5/ckeditor5/build/docs/ckeditor5/latest/features/image.html#resizing-images.

[oleq]

@ckeditor/qa-team Can you take a look at this PR? Thanks 🙏

[panr]

Localization entries are missing.
Missing changelog entry for ckeditor5-core.
Docs are bleeding (CKEditorError: imageresizeui-missing-icon)
http://fake.ckeditor.com/ck/5/ckeditor5/build/docs/ckeditor5/latest/features/image.html#resizing-images.

Fixed it.

[FilipTokarski]

I reported a bug with jumping blue border, which occurs also on master ( and since a long time ), but it gets much more visible when using those new buttons for resizing.

Original issue: #7633

Screencast:

[FilipTokarski]

Apart from what I mentioned above, everything seems to be ok 👍